Dengue Fever

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1. Manifestation of Dengue Infection

All four dengue virus (Den 1, 2, 3 and 4) infections may be asymptomatic or may lead to undifferentiated fever, dengue fever (DF), or dengue haemorrhagic fever (DHF) with plasma leakage that may lead to hypovolemic shock, dengue shock syndrome (DSS).

Manifestation of dengue virus infections:

2. Recognition of Dengue Fever/Dengue Haemorrhagic Fever (DF/DHF)

Dengue fever is an acute febrile illness of 2-7 days duration (sometimes with two peaks) with two or more of the following manifestations:

headache
retro-orbital pain
myalgia/arthralgia
rash
haemorrhagic manifestation (petechiae and positive tourniquet test') and,
leukopenia.

In children, DF is usually mild. In some adults, DF may be the classic incapacitating disease with severe bone pain and recovery may be associated with prolonged fatigue and depression.

Dengue Haemorrhagic fever is a probable case of dengue and haemorrhagic tendency evidenced by one or more of the following:

Positive tourniquet test
Petechiae, ecchymosis or purpura
Bleeding from mucosa (mostly epistaxis or bleeding from gums), injection sites or other sites
Haematemesis or melena
Thrombocytopaenia (platelets 100,000/cu.mm or less) and
Evidence of plasma leakage due to increased capillary permeability manifested by one or more of the following:

- A >20 per cent rise in haemotocrit for age and sex

- A >20 per cent drop in haemotocrit following treatment with fluids as compared to baseline

- Signs of plasma leakage (pleural effusion, ascites or hypoproteinaemia).

Dengue Shock Syndrome (DSS) All the above criteria of DHF plus signs of circulatory failure manifested by rapid and weak pulse, narrow pulse pressure (< or equal to 20 mm Hg); hypotension for age, cold and clammy skin and restlessness.

The above descriptions of DF/DHF/DSS are adequate for guiding doctors to treat the disease. However, for reporting of the disease, cases should be classified as suspected DF/DHF/DSS on the basis of above the criteria. Added serological evidence would categorize them into probable and confirmed cases. Serological and virological diagnosis is not possible in most small hospitals. It is recommended that blood samples of patients be sent to a laboratory according to the guidelines provided at Annex 1.

There are difficulties in categorizing the disease. A patient can progress from DHF to DSS, and depending on the stage of the disease when the patient reports, a mixed picture can be seen. However, as long as the patient evaluation is done systematically, there should be no difficulties in providing treatment, or in decision making about admission to a hospital, or in referring patients for specialised care.

3. Treatment of DF and DHF

3.1 Febrile Phase

In the early febrile phase, it is not possible to distinguish DF from DHF. Their treatments during the febrile phase are the same, i.e. symptomatic and supportive:

Rest.
Paracetamol (not more than 4 times in 24 hours) according to age for fever above 390C.
Do not give Aspirin or Brufen. Aspirin can cause gastritis and/or bleeding. In children, Reye's syndrome (encephalopathy) may be a serious complication.
Do not give antibiotics as these do not help.
Oral rehydration therapy is recommended for patients with moderate dehydration caused by vomiting and high temperature.
Food should be given according to appetite.

All dengue patients must be carefully observed for complications for at least -2 days after recovery from fever. This is because life threatening complications often occur during this phase. Patients and households should be informed that severe abdominal pain, passage of black stools, bleeding into the skin or from the nose or gums, sweating, and cold skin are danger signs. If any of these signs is noticed, the patient should be taken to the hospital. Detailed information which should be provided to all patients and households by the doctor is given in Annex 2. The patient who does not have any evidence of complications and who has been afebrile for 2-3 days does not need further observation.

3.2 Afebrile Phase

(1) Dengue Fever

Constitutional symptoms in patients with DF after the fall of fever are as during the febrile stage. Most patients will recover without complication. Treatment should be carried out as indicated in Chart 1.

(2) Dengue Haemorrhagic Fever (DHF) Grades I and It

As in DF, during the afebrile phase of DHF Grades I and II, the patient has the same symptoms as during the febrile phase. The clinical signs plus thrombocytopenia and haemoconcentration or rise in haematocrit are sufficient to establish a clinical diagnosis of DHF. During this phase, the patients should be observed for at least 2-3 days after the fall in temperature, for rashes on the skin, bleeding from nose or gums, blue spots on the skin or tarry stools. If any of these signs are observed, the patients should be brought to the hospital without delay. The only difference between the DF and DHF Grade I is the presence of thrombocytopenia and rise in haematocrit (>20 per cent). Patients with DHF Grade I do not usually require intravenous fluid therapy and ORT is sufficient. Intravenous fluid therapy may need to be administered only when the patient is vomiting persistently or severely, or refusing to accept oral fluids. Patients with DHF Grade I who live far away from the hospital or those who are not likely to be able to follow the medical advice should be kept in the hospital for observation.

During the afebrile phase of DHF Grade II, the complications usually seen, in addition to those observed during the DHF Grade I phase, are abdominal pain, black tarry stools, epistaxis, bleeding from the gums, and continued bleeding from injection sites. Immediately after hospitalization, haematocrit and platelet count must be carried out to assess the patient's condition. A reduction in the platelet count to £ 100,000/mm3 or less than 1-2 platelets/oil field (average of 10 oil field counts) usually precedes a rise in haematocrit. A rise in haematocrit of 20 per cent or more (e.g. increase from 35 per cent to 42 per cent) reflects a significant plasma loss and indicates the need for intravenous fluid therapy. Early volume replacement of lost plasma with Cystalloid3 solution (e.g. isotonic saline solution) can reduce the severity of the disease and prevent shock. Intravenous fluid therapy before leakage is not recommended. In mild to moderate cases of DHF Grade II, intravenous fluid therapy may be given for a period of 12-24 hours in a small hospital or short stay unit (OPD) of a large hospital. This is an important life saving measure.

Patients should be monitored on an hourly basis by medical personnel. Based on periodic haematocridplatelet count determinations and vital signs, the treatment should be reviewed and revised.

Source : WHO SEAR’O (Info)

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